Ford American Motorhomes based on the E450 chassis with the 6.0 litre common rail diesel engine was first introduced in the second quarter of the model year of 2003.
Prior to the introduction of the 6.0 litre engine, Ford used the 7.3 litre power stroke diesel, which developed 275 BHP in its last years of production. The 7.3 litre power stroke diesel was a turbo charged direct injection engine with a compression ratio of 17.5:1. During this time it was fitted with split shot injectors which allowed a small quantity of fuel to be introduced to the combustion chamber just before the main injection charge, this was to help reduce the sharp combustion knock.
Ultimately Ford now needed to introduce a new diesel engine for use in their light truck and motorhome chassis. The 7.3 litre engine was produced not by Ford but by a company called International, the same company that makes some farm machinery (International Combine Harvesters). Once again Ford looked to International for them to produce an engine.
Ford decided to buy the 6.0 litre diesel engine cylinder block and heads, and then modify it to produce more power and less emissions. They used a variable geometry turbo charger and a compression ratio 18.1 to meet the light emission law. Also they introduced EGR (exhaust gas recirculation), all of which will be explained later.
With all of these alterations Ford now had a 6.0 litre diesel engine which met the emission limitations, it was good on fuel and would produce 325 BHP which was 50 BHP more than its predecessor. This was a good result they thought. To produce more power comes as a positive, as with everything in life there is always a negative, that negative for Ford was heat.
EGR (exhaust gas recirculation), this in basic terms is when you take some of the exhaust gases and introduce them back into the inlet of the engines therefore burning them twice. The result of this is cleaner exhaust gases leaving the exhaust tail pipe. As I mentioned with the increase of BHP came the increase of heat. To introduce very hot exhaust gases into the combustion chamber will reduce the engines efficiently. The reason for this is when the cold air is very cold it is much denser (more of it). When you introduce cold air into the cylinder and then heat it up (with the use of compression) you get more air into the cylinder which then produces more power. Ford pass these hot exhaust gases through a cooler which is connected to the cooling system.
The exhaust gas cooler in the combustion chamber that Ford used expanded. When the engine was producing very hot gases (full load) and contracted when the engine produced cooler exhaust gases (light load). This expansion and contraction caused the coolers to fail, allowing exhaust gases to enter the cooling system and in turn pressurised the coolant system forcing the water out of the radiator cap. If this was not noticed, the lack of coolant would crack the cylinder heads and blow the head gaskets.
This problem is applicable to the American motorhomes, in the fact that it is caused by discharged batteries. This problem has been found to be with the electronic control module that operates the injectors and is caused by low voltage from the batteries. The injector control module multiplies the battery voltage to operate the diesel injectors from 12 to 48 volts, the symptoms are that the engine turns but does not fire or alternatively just stops.
A problem that should not potentially effect the American RV motorhome owner – cylinder head gasket failure. As I pointed out earlier the engine originated from International Harvester. The old 7.3 engine had 6 bolts per cylinder head, whereas the 6.0 litre only had 4, and with the engine working at full load which means maximum turbo boost, a cylinder head gasket failure was not unusual.
Turbo charger failure is not uncommon on motorhomes as they are usually not driven very hard. What usually happens is the variable vain part of the turbo gets large deposits of carbon around it, therefore restricting the vane movement. This problem might be averted with a fuel additive to reduce the carbon.
Here we have pointed out some of the well documented problems that have cost Ford a large amount of money. The engine has now been phased out due to its questionable reliability. In 2008 the 6.0 litre engine was replaced by the 6.4 litre power stroke twin turbo charged (factory fitted) engine.